[llvm] [Hexagon] Do not optimize address of another function's block (PR #101209)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-hexagon

Author: None (yandalur)

<details>
<summary>Changes</summary>

When the constant extender optimization pass encounters an instruction that uses an extended address pointing to another function's block, avoid adding the instruction to the extender list for the current machine function.

---
Full diff: https://github.com/llvm/llvm-project/pull/101209.diff


2 Files Affected:

- (modified) llvm/lib/Target/Hexagon/HexagonConstExtenders.cpp (+4) 
- (added) llvm/test/CodeGen/Hexagon/cext-opt-block-addr.mir (+173) 


``````````diff
diff --git a/llvm/lib/Target/Hexagon/HexagonConstExtenders.cpp b/llvm/lib/Target/Hexagon/HexagonConstExtenders.cpp
index f0933765bbcbd..86ce6b4e05ed2 100644
--- a/llvm/lib/Target/Hexagon/HexagonConstExtenders.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonConstExtenders.cpp
@@ -1223,6 +1223,10 @@ void HCE::recordExtender(MachineInstr &MI, unsigned OpNum) {
   if (ER.Kind == MachineOperand::MO_GlobalAddress)
     if (ER.V.GV->getName().empty())
       return;
+  // Ignore block address that points to block in another function
+  if (ER.Kind == MachineOperand::MO_BlockAddress)
+    if (ER.V.BA->getFunction() != &(MI.getMF()->getFunction()))
+      return;
   Extenders.push_back(ED);
 }
 
diff --git a/llvm/test/CodeGen/Hexagon/cext-opt-block-addr.mir b/llvm/test/CodeGen/Hexagon/cext-opt-block-addr.mir
new file mode 100644
index 0000000000000..9f140132dcd6c
--- /dev/null
+++ b/llvm/test/CodeGen/Hexagon/cext-opt-block-addr.mir
@@ -0,0 +1,173 @@
+# REQUIRES: asserts
+# RUN: llc -march=hexagon -run-pass hexagon-cext-opt %s -o - | FileCheck %s
+
+# Check that the HexagonConstantExtenders pass does not assert when block
+# addresses from different functions are used
+# CHECK-LABEL: name: wibble
+# CHECK: A2_tfrsi blockaddress(@baz
+# CHECK: A2_tfrsi blockaddress(@wibble
+
+--- |
+  target triple = "hexagon"
+
+  define dso_local void @baz() {
+  bb:
+    br label %bb1
+
+  bb1:                                              ; preds = %bb
+    %call = tail call fastcc i32 @wibble(i32 poison)
+    ret void
+  }
+
+  define internal fastcc i32 @wibble(i32 %arg) {
+  bb:
+    %call = tail call i32 @eggs(i32 noundef ptrtoint (ptr blockaddress(@baz, %bb1) to i32))
+    br label %bb1
+
+  bb1:                                              ; preds = %bb
+    tail call void @baz.1(i32 noundef ptrtoint (ptr blockaddress(@wibble, %bb1) to i32))
+    ret i32 %call
+  }
+
+  declare i32 @eggs(i32 noundef) local_unnamed_addr
+
+  declare void @baz.1(i32 noundef) local_unnamed_addr
+
+...
+---
+name:            baz
+alignment:       16
+exposesReturnsTwice: false
+legalized:       false
+regBankSelected: false
+selected:        false
+failedISel:      false
+tracksRegLiveness: true
+hasWinCFI:       false
+callsEHReturn:   false
+callsUnwindInit: false
+hasEHCatchret:   false
+hasEHScopes:     false
+hasEHFunclets:   false
+isOutlined:      false
+debugInstrRef:   false
+failsVerification: false
+tracksDebugUserValues: false
+registers:
+  - { id: 0, class: intregs, preferred-register: '' }
+liveins:         []
+frameInfo:
+  isFrameAddressTaken: false
+  isReturnAddressTaken: false
+  hasStackMap:     false
+  hasPatchPoint:   false
+  stackSize:       0
+  offsetAdjustment: 0
+  maxAlignment:    1
+  adjustsStack:    false
+  hasCalls:        false
+  stackProtector:  ''
+  functionContext: ''
+  maxCallFrameSize: 4294967295
+  cvBytesOfCalleeSavedRegisters: 0
+  hasOpaqueSPAdjustment: false
+  hasVAStart:      false
+  hasMustTailInVarArgFunc: false
+  hasTailCall:     true
+  isCalleeSavedInfoValid: false
+  localFrameSize:  0
+  savePoint:       ''
+  restorePoint:    ''
+fixedStack:      []
+stack:           []
+entry_values:    []
+callSites:       []
+debugValueSubstitutions: []
+constants:       []
+machineFunctionInfo: {}
+body:             |
+  bb.0.bb:
+    successors: %bb.1(0x80000000)
+
+  bb.1.bb1 (ir-block-address-taken %ir-block.bb1):
+    %0:intregs = IMPLICIT_DEF
+    $r0 = COPY %0
+    PS_tailcall_i @wibble, hexagoncsr, implicit $r0
+
+...
+---
+name:            wibble
+alignment:       16
+exposesReturnsTwice: false
+legalized:       false
+regBankSelected: false
+selected:        false
+failedISel:      false
+tracksRegLiveness: true
+hasWinCFI:       false
+callsEHReturn:   false
+callsUnwindInit: false
+hasEHCatchret:   false
+hasEHScopes:     false
+hasEHFunclets:   false
+isOutlined:      false
+debugInstrRef:   false
+failsVerification: false
+tracksDebugUserValues: false
+registers:
+  - { id: 0, class: intregs, preferred-register: '' }
+  - { id: 1, class: intregs, preferred-register: '' }
+  - { id: 2, class: intregs, preferred-register: '' }
+  - { id: 3, class: intregs, preferred-register: '' }
+  - { id: 4, class: intregs, preferred-register: '' }
+liveins:         []
+frameInfo:
+  isFrameAddressTaken: false
+  isReturnAddressTaken: false
+  hasStackMap:     false
+  hasPatchPoint:   false
+  stackSize:       0
+  offsetAdjustment: 0
+  maxAlignment:    1
+  adjustsStack:    true
+  hasCalls:        true
+  stackProtector:  ''
+  functionContext: ''
+  maxCallFrameSize: 4294967295
+  cvBytesOfCalleeSavedRegisters: 0
+  hasOpaqueSPAdjustment: false
+  hasVAStart:      false
+  hasMustTailInVarArgFunc: false
+  hasTailCall:     false
+  isCalleeSavedInfoValid: false
+  localFrameSize:  0
+  savePoint:       ''
+  restorePoint:    ''
+fixedStack:      []
+stack:           []
+entry_values:    []
+callSites:       []
+debugValueSubstitutions: []
+constants:       []
+machineFunctionInfo: {}
+body:             |
+  bb.0.bb:
+    successors: %bb.1(0x80000000)
+
+    %2:intregs = A2_tfrsi blockaddress(@baz, %ir-block.bb1)
+    ADJCALLSTACKDOWN 0, 0, implicit-def $r29, implicit-def dead $r30, implicit $r31, implicit $r30, implicit $r29
+    $r0 = COPY %2
+    J2_call @eggs, hexagoncsr, implicit-def dead $pc, implicit-def dead $r31, implicit $r29, implicit $r0, implicit-def $r29, implicit-def $r0
+    ADJCALLSTACKUP 0, 0, implicit-def dead $r29, implicit-def dead $r30, implicit-def dead $r31, implicit $r29
+    %3:intregs = COPY $r0
+
+  bb.1.bb1 (ir-block-address-taken %ir-block.bb1):
+    %4:intregs = A2_tfrsi blockaddress(@wibble, %ir-block.bb1)
+    ADJCALLSTACKDOWN 0, 0, implicit-def $r29, implicit-def dead $r30, implicit $r31, implicit $r30, implicit $r29
+    $r0 = COPY %4
+    J2_call @baz.1, hexagoncsr, implicit-def dead $pc, implicit-def dead $r31, implicit $r29, implicit $r0, implicit-def $r29
+    ADJCALLSTACKUP 0, 0, implicit-def dead $r29, implicit-def dead $r30, implicit-def dead $r31, implicit $r29
+    $r0 = COPY %3
+    PS_jmpret $r31, implicit-def dead $pc, implicit $r0
+
+...

``````````

</details>


https://github.com/llvm/llvm-project/pull/101209